It seems I've gotten some algae problems for the first time, and could use some help from people with experience.
There's a greenish "powder" all over the bottom and lower sides of the pool. It is easy to scrub away, making clouds in the water, and the filter cartridge becomes dark green. When it was at its worst, free chlorine dropped to 0, with Total Cl of about 2. The pool sides are though not slippery. I guess this is green algae?
I treated by shocking with 0,4 litres of dichlor, which should give about 13ppm in my 17.000 litre pool. This stopped the algae growth, and I thought everything was ok. Today, 5 day after the shock treatment, the free Cl is still at about 8-10ppm (!), and algae seems to start growing again. Can algae grow at that level of Cl, and if there is algae wouldn't the Cl level drop more quickly? It is possible that I have a high CYA level though.
pH: 7,2 - 7,4 (phenol red tablets)
Alk: 50 - 150 (test strips....)
CYA: 0 (test strips... )
Free Cl: 8-10ppm (DPD tablets, measured mixture of 1 part pool water and 3 parts tap water, DPD reading is about 2,5ppm)
Tot Cl: Not measured recently.
The CYA level could be high: IĀ“ve used about 2 - 4kg in total of trichlor and dichlor this season, which should give 60-120 ppm CYA in my 17000 litres (if I calculated correctly). But the test strip shows nothing... I've been trying to measure CYA with strips since I bought the pool four years ago, but never got them to show anything. I've always thought that since I change water every season I never used enough tri/dichlorine in one year to make a difference, but now after trying to calculate the added CYA IĀ“m not so sure.
This year I started using dichlor for shocking, partly because I got it very cheap, and partly to try to get some CYA in the pool. Now I have algae for the first time, maybe not a coincidence...
Anybody had experience of test strips showing zero CYA when there actually is a high level of CYA?
Finally, anybody knows how to get a good test kit in Sweden? They donĀ“t ship the TF-100 to Sweden...
My alternatives for CYA measuring is my Aquacheck strips (seems not working) or the LaMotte ColorQ, which is very expensive and still not very reliable?